Lubricating oils



atented ay i, 1943 F i CE Thomas, Jinn, Stamford, Conn, AmericanCyanamid Company,

assignors to New York,

N. iL, a corporation of Maine No Drawing. Application Qctober 31, 1941,Serial No. 417,311

'2' Claims. '(iUl. 252-426) This invention relates to lubricating oils,particularly those of the type known as crankcase oils. Although thelubricating oils of the present invention are highly desirable for usein crankcases of passenger automobiles they are especially valuable forheavy duty use in truck, bus, aeroplane, marine and Diesel engines whichoperate for long periods of time at high temperatures.

The principal objects of the invention are to provide a lubricating oilof the heavy duty type which possesses excellent detergent properties,is resistant to oxidation and sludge formation, is non-corrosive toalloy bearings and other metal parts under conditions of extreme serviceand which is free from film formation and ring sticking tendencies.

These objects, and others which will appear hereinafter, areaccomplished by us by providing a hydrocarbon lubricating oil containinga class of compounds having detergent, and other desirable properties.These compounds are designated broadly as acyl phenol monosulfideshaving the general formula Reem mrm la Y Y When conventional lubricatingoils are sub-- jected to high operating temperatures for long periods oftime, as in heavy duty service, they tend to decompose with theformation of complex and objectionable oxidation and decompositionproducts. Under the high temperature conditions obtaining in the enginethese decomposition products polymerize to form lacquer-like deposits onor between the moving parts causing these parts to stick. Even largerquantities of polymerization products remain dispersed in the partlyoxidized crankcase oil. and are rapidly precipitated and form a sludgewhen the engine cools or when fresh oil is added to the engine. Theseprec pitated sludges become caked on heated metal surfaces and cut downthe effective life of the engine.

A number of oil soluble detergents of the type of metal soaps,phenolates and alcoholates have been proposed and used in crankcase oilsto dissolve or disperse the sludge and prevent lacquer deposits andstuck piston rings. Unfortunately, however, the great majority of thesesubstances increase the rate of oxidation in a manner somewhat analogousto the accelerating action of the various metallic soaps or driers onthe oxidation of varnish films, and their presence results in anincreased concentration of acidic oxidation products in the oil.Increased quantities of these acidic oxidation products in the oilcreate in turn an even more serious difficulty for they attack andcorrode alloy bearings commonly employed in internal combustion engines.Alloys composed of copper-lead, silver-cadmium, nickelcadmium, etc. arewidely used and are subject to attack by the acidic oxidation productsformed in the oil.

Certain anti-corrosion agents which have no detergent properties, suchas triphenyl phosphite and sulfurized sperm oil, have been added tolubricating oils in order to counteract the corrosive effect of theoxidation products of the oil. Although the detergents which have beenpreviously mentioned and the anti-corrosion agents perform theirindividual functions in lubricating oils the two separate chemicals donot cooperate to produce a satisfactory anticorrosion and detergentaction when used together. The function of a. corrosion inhibitor is tocover the bearing surfaces and other corrodable parts of the engine witha passivating film that prevents corrosion of the metal by the organicacids and other corrosive productsin the oil. A detergent, as its nameimplies, operates to remove adhering solids in the metal parts of theengine and thus produce a clean metal surface. Consequently mixtures ofa detergent with a corrosion inhibitor have proven to be in effectiveover any extensive period of time since the detergent action of thesludge inhibitor tends to remove the corrosion inhibitor from the metalsurface thus rendering it ineffective for the purpose intended.

The acyl phenol monosulfides and metal salts thereof which we employavoid the above described difiiculties by possessing detergent,antisludging and corrosion inhibiting action in the single compound. Thecompounds are heatstable and are not easily decomposed in the oilbecause of the high operating temperatures often encountered. They arealso practically 'waterinsoluble and are not extracted from the oil bycontact with water. In addition to their detergent and dispersingproperties they have oiliness properties and many of them also-act tolower the pour point of the oil.

The acyl phenol monosulfides and their metal salts which we employ areso very efiective that it is possible to improve lubricating oils toa-great extent by the, use of very small amounts of the compounds. Inlubricating oils intended for ordinary service where high temperaturesoccur only occasionally, from 0.1-0.8% of the acyl phenol monosulfide orits salt issufilcient. In heavy duty service it is generally advisableto use a little more, as for example 0.5-3.0% in the oil.

The extremelyhigh solubility of these compounds in hydrocarbon oilsleads to another important advantage, namely, the ease with which thesecompounds are blended with lubricating oils. This step is furthersimplified by our practice of dissolving them in ordinary types oflubricating oils to the extent of 50-80% for storage and shippingpurposes. For this reason it will be understood that, the appendedclaims are intended to cover lubricating oil compositions of such highconcentration unless otherwise limited.

The acyl phenolate monosulfides which we employ to prepare the improvedlubricating oils of our invention are made by reacting an alkylsubstituted phenol monosulfide with an acyl halide in the presence ofanhydrous aluminum chloride. Ordinarily we employ 2 moles of theacylating agent for each mole of the phenol monosulfide in order thateach phenyl radical of the phenol monosulfide may be substituted with atleast one acyl group. Th reaction may be carried out in either one ortwo steps, i. e. the phenol monosulfide may be first reacted with theacyl halide followed by the addition of aluminum chloride and furtherreaction, or all of these reactants may be mixed together and themixture heated. In either caseheating is continued until the evolutionof hydrogen chloride which is eliminated in the reaction has subsided.The product of this reaction is probably a complex aluminum salt of theacyl phenol monosulfide. This product is then decomposed by the additionof an excess of cold dilute hydrochloric acid.

The acyl phenol monosulfide thus formed may be separated from thereaction mixture by extraction with a solvent followed by washing andevaporation of the solvent. Various metal salts of the acyl phenolmonosulfide may be obtained by neutralization with an appropriatesalt-forming base or by double decomposition with its sodium salt. Thecompounds thus prepared are straw-colored to dark reddish-brown liquidsof varying viscosity and are found to be extremely soluble in gasolineand lubricating oils.

The alkyl substituted phenol monosulfides which we employ in the abovereaction are wellknown products having the general structural formula:

in which R1 and R2 are alkyl groups of 1-20 carbon atoms and in whichthe OH group may occupy a. position either ortho or para to the sulfurlinkage. The alkyl groups R1 and R2 tend to promot solubility of thecompounds in lubricating oils and in general the longer the chain themore soluble the compounds will be in oil.

' The acyl halides which we employ may be of different kinds such as forexample butyroyl chloride, caproyl chloride, lauroyl chloride myristoylchloride, stearoyl chloride, benzoyl chloride, amyl benzoyl chloride,amyl oxyacetyl chloride, naphthenoyl chloride, phenyl acetyl chloride,phenoxy acetyl chloride, phenyl stearoyl chloride and many others. Thenaphthenoyl chloride mentioned above is composed of a mixture of variouscycloaliphatic acyl halides such as are prepared from naphthenic acids,a product of the petroleum industry.

The metal radicals which we introduce into the acyl phenol monosulfidemolecule to form salts thereof include those metal salt-forming radicalssuch as aluminum, lead, zinc, magneslum, calcium, barium, strontium,etc. The metal salts may be prepared by simply neutralizing the acylphenol monosulfide with an appropriate metal oxide or hydroxide or bymethods of double decomposition, as illustrated in the specific example.We prefer to employ the alkaline earth metal salts of these compounds inour improved lubricating oil compositions.

The preparation of a number of these acyl phenol monosulfides and saltsthereof will now be described in detail in the following examples. Itshould be understood, however, that this description is given merely forpurposes of illustration and our invention is not to be limited to theparticular compounds or the particular method of preparation describedsince other acyl phenol monosnlfldes may be employed without departingfrom the scope of the invention as set forth in the appended claims.

EXAMPLE 1 2-stearoz/l-4-amyl phenol monosulfide 92 parts by weight of4-amyl phenol monosulfide was dissolved in parts of A. S.,T. M. and 153parts of stearoyl chloride added with stirring. The mixture was thenheated under a reflux condenser With stirring for 30 minutes after whichtime the evolution of hydrogen chloride had subsided. After cooling, 23parts of anhydrous aluminum chloride was added and the resulting mixtureheated to refluxing temperatures with stirring. Refluxing and stirringwere continued for 2 hours, at the end of which time very littlehydrogen chloride was being evolved. The reaction mixture was thencooled and 200 parts of cold dilute hydrochloric acid added. The mixturewas stirred thoroughly and parts by weight of toluene added. The aqueouslayer was then separated and the solvent layer Washed once with warm,dilute hydrochloric acid and twice with hot water. The solvent was thenevaporated and 2-stearoyl-4-amyl phenol monosulfide recovered as areddish-brown liquid, readily soluble in gasoline and lubricating oil,but practically insoluble in water.

EXAMPLE 2 9.5 parts by weight of barium the barium hydrate had reactedand the water of neutralization had been expelled. Toluene was addedfrom time to time to replace the solvent evaporated. After cooling, thesolution was filtered from traces of inorganic barium salts and thesolvent removed by evaporation. The barium salt thus obtained was anextremely viscous reddish-brown liquid believed to have the followingformula:

Because of the high viscosity of this product, it is preferable to add aquantity of light lubricating oil before the solvent is completelyevaporated. By doing this a 50% solution of the barium salt of2-stearoyl-4-amyl phenol monosulfide in lubricating oil is obtainedwhich is much more convenient for handling and blending.

EXAMPLE "3 The heavy metal salts of Z-stearoyl-d-amyl phenolmonosulfide, such as those of tin and zinc, may be conveniently preparedby double decomposition in an ethanol-toluene solution, between thesodium salt of 2-stearoyl-4-amyl phenol monosulfide and the appropriatemetallic inorganic salt.

For example, 30 parts of 2-stearoyl-4-amyl phenol monosulfide wasdissolved in a mixture of 30 parts of ethanol and parts of toluene. 2'?parts of a sodium ethylate solution, prepared by dissolving 23 parts ofmetallic sodium in 377 parts of ethanol, was heated and the mixturewarmed up to 75 C. until homogeneous. The temperature.v was then droppedto about 50 C. and 6.4 parts of stannous chloride, dissolved in parts ofethanol, was gradually added with stirring.

The mixture was then heated to 75 C. and

parts of toluene added. After cooling, the solution was filtered fromsodium chloride and the filtrate evaporated. The st'annous salt of 2-stearoyl-l-amyl phenol monosulfide remained as a viscous, reddish-brownproduct.

EXAMPLE 4 The aluminum. salt of 2-stearoyl-4-amyl phenol monosulfide wasprepared by dissolving 20 parts of the product prepared in Example 1 in40 parts of toluene followed by the addition of 5 parts of aluminumbutylate. The mixture was stirred and heated at 110 C. for 30 minutes.The solvent was then evaporated, the last traces under reduced pressure,and the aluminum salt of 2- stearoyl-4-amyl phenol monosulfide recoveredas a'viscous, reddish-brown liquid.

This compound was prepared by condensing 2 moles of lauroyl chloridewith 1 mole of 4-amyl phenol monosulfide in the presence of 0.70 mole ofanhydrous aluminum chloride following the procedure described in detailin Example 1. The product was a yellow colored liquid insoluble in waterbut easily soluble in gasoline and lubricating oils.

The various metallic salts of this compound were prepared in the samemanner described in Examples 2 to 4.

EXAMPLE 6 2-butyryl-4-amyl phenol monosulfide OH OH CaH1CO This productwas prepared by condensing 2 moles of butyryl chloride with 1 mole of4-amyl phenol monosulfide in the presence of 0.70 mole of anhydrousaluminum chloride. The product was a straw colored liquid insoluble inwater but easily soluble in gasoline and lubricating oil. The variousmetal salts are prepared as previously described.

EXAMPLE 7 2 -stearoyl4-methyl phenol monosulfide en 0 ll CnUarr-UO- -S'CEO-(11111.15

l 0 Ha C H:

This compound was prepared by condensing 2 moles of stearoyl chloridewith 1 mole of ii-methyl phenol monosulfide in the presence of 0.70 moleof anhydrous aluminum chloride by the procedure described in detail inExample 1. The product was a yellow liquid insoluble in water andreadily soluble in gasoline and lubricating oil.

EXAMPLE 8 EXAMPLE 9 d-stearoyl-Z-amyl phenol monosulfide O 0 H H (7unis-'0 ([7-(3 nHas CsHn 051111 This compound was prepared by condensing2 moles of stearoyl chloride and 1 mole of p-(2 amyl phenol) monosulfidein the presence of 0.70 mole of anhydrous aluminum chloride. The productwas a reddish-brown liquid insoluble in water but easily soluble ingasoline and lubricating oil.

EXAMPLE 100 parts by weight of 6-stearoyl-2-amyl phenol monosulfide wasdissolved in 70 parts of ethanol and 120 parts of toluene andneutralized with barium hydrate. The solution was then filtered and thesolvent evaporated, leaving the barium salt of 6-stearoyl-2-amyl phenolmonosulfide as a thick reddish-brown liquid.

EXAMPLE l1 Z-naphthenoyZ-el-amyl phenol monosulfide dissolved in analcohol-toluene solution.

EXAMPLE 12 Z-naphthenoyl-ai-methyl phenol monosulfide This compound wasprepared by condensing 104 parts of naphthenoyl chloride with 50 partsof p-cresol monsulfide dissolved in 50 parts of naphtha solution in thepresence of parts of anhydrous aluminum chloride. The product was abrown liquid practically insoluble in water but readily soluble ingasoline and lubricating oil.

The barium salt of this compound was prepared by heating 35 parts of2-naphthenoyl-4-methyl phenol monosulfide, dissolved in parts of ethanoland 50 parts of toluene, with 5 parts of barium hydrate. The product wasa viscous, stiif, brown colored liquid which Was blended with 50% of alight lubricating oil for ease of handling.

The effectiveness of the above-described compounds in preventingcorrosion of bearings in lubricating oils, under conditions of severeservice, is demonstrated by the following results obtained by subjectinga S. A. E. No. 10 solvent refined Mid-Continent oil to the StandardCatalytic Indiana test. Samples of the oil containing varying amounts(OB-0.4%) of the acyl phenol monosulfide were compared with the oilcontain-' ing no additive.

TABLE I Catalytic Indiana test Mid-Continent solvent refined oil 70hours at 341 F. Copperdead bearing TABLE II Catalytic Indiana testSolvent refined Pennsylvania oil Bearing \ddithu loss, mg.

Cu-Ph (.ontrol 201 Barium 2-stcaroyl-4-amyl phenol monosulfide. 0.3 102-stearogl-4-amyl phenol monosulfide 0.3 2 2-napht enoyl-i-nmyl phenolmonosulfide"... 0 4 RI! 4 ill) 2-butyryl4-amyl phenol monosulfide 0:

1 Yl i i."

in which R1 and R2 are alkyl groups having 1 to 20 carbon atoms and R3and R4 are members of the group consisting of alkyl, aryl, alkoxyalkyl,aroxyalkyl, aralkyl, alkaryl and cycloalkyl radicals and metal saltsthereof.

2. A lubricating oil composition containing a predominating amount of alubricating oil 'and (Ll-3% of a compound selected from the groupconsisting of acyl phenol monosulfides of the general formula generalformula $1) Oil H0 0 aamss o tt Y in which R1 and R2 are alkyl groupshaving 1 to 20 carbon atoms and R3 and Br are members of the groupconsisting of alkyl, aryl, alkoxyalkyl, aroxyalkyl, aralkyl, alkaryl andcycloalkyl radicals and alkaline earth metal salts thereof.

4. A lubricating oil composition containing a predominating amount of alubricating oil and a minoramount of a compound selected from-the groupconsisting of acyl phenol monosulfides of minor amount of2-stearoyl-4-amyl phenol monothe general formula, sulfide.

o OH HO O 6. A lubricating oil composition containing a II IIpredominating amount of a lubricating oil and 5 a minor amount of thebarium salt of 2-stearoyl- I 4-amyl phenol monosulfide.

'I. A lubricating oil composition containing a predominating amount of alubricating oil and a minor amount, of the barium salt of 2-lauroylinwhich R1 and R2 are alkyl groups having 1 to 10 4-amy1 phenolmonosulfide. 20 carbon atoms and metal salts thereof.

5. A lubricating oil composition containing a I ELMER W. COOK.predominating amount of a lubricating oil and a WILLIAM D. THOMAS, JR.

